Bar code technology is mainly implemented on the surface of an article or as a label on its encapsulation or package. It contains information related to properties of the article itself, such as place of origin, type, name, price, and so on. The corresponding digital identification of a traditional bar code is often represented by a set of parallel rows, the information of which is implemented by changing a row width and a gap therebetween, which is referred to as a linear or one-dimensional bar code information system. In addition, bar code technology has also been developed into a two-dimensional bar code system, which includes rectangle, dot, hexagon, and other geometric patterns. This type of bar code can be identified by using a special optical scanner, i.e., a bar code reader.
The geometric patterns used within a bar code and the use of an optical bar code reader result in the following problems:
1) the label of the bar code is large in size, usually on theorder of a centimeter, and it thus takes up a large space;
2) the label of the bar code is has poor security, because it can be identified by records or the like, such that that confidentiality requirements cannot be met;
3) the optical reading system has a high requirement for cleanliness of the environment in which the bar code is to be read, it is therefore vulnerable to interference from dust, so that the reading often needs to be performed for multiple times.